The invention relates generally to intelligent battery systems comprising a battery pack with electronic circuitry to monitor battery parameters, and an associated battery charger. The invention deals more particularly with apparatus and processes for minimizing power dissipation by the electronic circuitry, and providing two-way communication between the battery pack and the battery charger.
A previously known battery pack with a microprocessor was disclosed in U.S. Pat. No. 4,289,836 to Lemelson. The microprocessor monitors battery parameters such as the state of battery charge, number of charging cycles, battery temperature, and battery pressure. The microprocessor may also be used to control a display for the battery parameters. The battery pack is coupled to a simple power supply for recharging purposes.
Another previously known battery pack is disclosed in U.S. Pat. No. 4,553,081 to Koenck which battery pack includes a microprocessor secured to a battery housing. The microprocessor monitors battery operation to determine remaining battery capacity, and counts the number of shallow discharges and successive recharging cycles to estimate deterioration of the battery. Circuitry within the battery pack occasionally causes a discharge of the battery to determine present battery capacity. The microprocessor and other circuitry require little operating power so that the shelf-life of the battery pack is long. The microprocessor is also coupled to a display for indicating battery capacity and other information obtained from the battery.
The battery pack of U.S. Pat. No. 4,553,081 also includes several I/O ports to communicate with a portable computer terminal device and a battery charger.
A general object of the present invention is to provide a battery pack which includes electronic circuitry to monitor battery parameters, which electronic circuitry draws minimal average power.
Another general object of the present invention is to provide a battery pack of the foregoing type and an associated battery charger which can provide two-way communication between each other via a small number of interconnections.
A more specific object of the present invention is to provide a battery pack of the foregoing type which accurately monitors battery discharge and charge.